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Keycloak SAML Broken has Authentication Bypass by Primary Weakness

High severity GitHub Reviewed Published Mar 5, 2026 to the GitHub Advisory Database • Updated Mar 6, 2026

Package

maven org.keycloak:keycloak-broker-saml (Maven)

Affected versions

<= 1.8.1.Final

Patched versions

None

Description

A flaw was found in org.keycloak.broker.saml. When a disabled Security Assertion Markup Language (SAML) client is configured as an Identity Provider (IdP)-initiated broker landing target, it can still complete the login process and establish a Single Sign-On (SSO) session. This allows a remote attacker to gain unauthorized access to other enabled clients without re-authentication, effectively bypassing security restrictions.

A fix is available at https://github.com/keycloak/keycloak/releases/tag/26.5.5.

References

Published by the National Vulnerability Database Mar 5, 2026
Published to the GitHub Advisory Database Mar 5, 2026
Last updated Mar 6, 2026
Reviewed Mar 6, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(62nd percentile)

Weaknesses

Authentication Bypass by Primary Weakness

The authentication algorithm is sound, but the implemented mechanism can be bypassed as the result of a separate weakness that is primary to the authentication error. Learn more on MITRE.

CVE ID

CVE-2026-3047

GHSA ID

GHSA-8cr3-vpxx-92cx

Source code

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